Formation by an upsetter is a method in which a round bar material is gripped with an electrode to apply electric current between the electrode and a round bar end, and is pressurized from the other end, thereby bulge-forming its heated end into a ball shape at a forming stage provided on the front surface of the upsetter, and the method has been commonly used for a forging press device for valve.
Then, it takes more than ten seconds to several tens of seconds to perform primary formation in an upsetter. On the other hand, it takes only one second to several seconds to perform secondary formation (pressing) by a forging press main body, and therefore, in order to increase production efficiency of the valve forging press, for example, about four upsetters are combined with one forging press.
To describe in detail, with respect to a conventional forging press device for valve composing a valve forging automation line, as described in the section of the conventional art in the following Patent Document 1, the upsetters are arrayed in one line on one side of the forging press main body, and primary formed workpieces formed in the respective upsetters are dropped into a chute by an ejector, to pass through the chute, and thereafter, those are dropped onto a top-chain conveyor, to reach a primary formed workpiece receiver in the vicinity of the forging press main body, to stop. Here, a multi-jointed robot installed in front of the forging press main body goes to take the primary formed workpieces, to carry those into a metallic mold of the forging press, and a workpiece carry-out device carries secondary formed workpieces out at the same time of completion of forging press.
However, in the aforementioned forging press device (the device described in the section of the conventional art in Patent Document 1), the primary formed workpieces are conveyed only from the one side of the forging press main body to the vicinity of the forging press main body. Therefore, there is the problem that it takes time to convey the workpieces from the upsetter located furthest from the forging press main body by the delivery conveyor, and the like, that is, a time required for production per secondary formed workpiece is long, which is extremely unproductive.
Then, as shown in the invention of the following Patent Document 1, there has been proposed a forging press device in which upsetters, delivery conveyors, and primary formed workpiece carry-in devices are disposed on the both sides centering on the opening of the forging press main body, and primary formed workpieces are carried-in from the both sides of the forging press main body, thereby shortening a time required for production per secondary formed workpiece.